Panasonic RP-HT710 and Sennheiser HD 419
(flat-plate measurements)
Two popular "dirt-cheap" headphones from the past. The "borderline" category of headphones.
February 16, 2025
The following is a measurement of two headphones that are no longer available in stores. These headphones represent a "borderline" category between hifi and budget: too valuable to be in the budget category, but far from an "audiophile's dream".
The measurements are simple flat-plate measurements, nothing special. With this method, we measure the headphone cup + driver frequency response, which is acceptable for large (over-ear) headphones.
One of the drawbacks of flat-plate measurements is that the leakage is higher with real or silicone ears than with flat-plate. As a result, bass response is overestimated in flat-plate measurements. Flat-plate measurements can be (and should be) supplemented with silicone ear measurements to get a better picture of low frequency performance.
The correction curve is obtained by subtracting the frequency response from the reference or target curve (it's enough to mirror the frequency response to the zero dB axis above 150 Hz). In most cases, it is impossible to correct response errors with a simple bass-mid-treble type equalizer, so a parametric equalizer or an equalizer with at least 15 bands is needed. (Voicemeeter - a free EQ, mixer and booster for Windows.)
The basic rule of EQ correction is to avoid boosting frequency bands by more than 6 decibels, especially below 100 Hz (distortion...). If more than 6 dB boost is needed, it's worth looking for another solution.
Important note (2026-07-22): I realized that in my silicone ear measurements the drop below 100 Hz is larger than the "typical". At 20 Hz, the difference between in-ear and flat plate measurement is only about 5 dB. It was my fault and not the fault of silicone ear measurements.
Panasonic RP-HT710
I wonder how many Panasonic RP-HT710s are left in good condition (if there is any...). These headphones were a big hit around 2005, good value for money, but their sound... The bass performance is weak, and the treble range is boosted. These headphones are not good to listen to without a correction EQ. On the other hand, the earcups are quite large and comfortable. The build quality is average at best, the internal wire at the hinge can break and the hinge can fell out after a few years (the loose hinge can be fixed with a "cable tie"). These headphones are sensitive and easy to drive, so they can be played at very loud level from an output with 1 VRMS maximum voltage, even after equalization. The channel matching is poor, there is a fairly large (two decibels) difference between the two sides, but the correction is easy with a "balance pot".
This headphone has "angled drivers", which is not common in this price range. The "angling" has a subtle effect on the concha response.
This is what a Panasonic RP-HT710 looks like:
Equalization has dramatic effect on the tone.
Sennheiser HD 419
The same can be said about the HD 419. It has better bass performance, but its sensitivity is a bit lower and the distortion is high below 100 Hz at high volume. This headphone doesn't like bass boosted or "bass heavy" material. The cups are a bit small and while the comfort is not bad, it takes some time to get used to it. The ear pads are replaceable and the built quality is quite good (except for the thin cable, which doesn't last long).
PRTF measurements
2026.07.24.
PRTF stands for Pinna Related Transfer Function, the response of the pinna with a specific headphone. PRTF measurements were made with a silicone ear ordered from AliExpress, flush mounted as it should be. Unfortunately, the silicone ear is a bit smaller than the average human ear. Besides, there is no available PRTF target for this ear, so I created a diffuse-field PRTF from a research paper ("Determination of noise immission from sound sources close to the ears", Hammershøi, Møller, 2008). So the PRTF target is not particularly for this ear, but better than nothing.
The measurements look promising, the Panasonic has better PRTF, but the HD 419 response is also acceptable.
The peak at 2.8 kHz in the Panasonic PRTF response is "not there", it is an artifact of PRTF measurements. The resonance (actually anti-resonance) present in the flat plate response is attenuated by the silicone ear. This appears as a peak in the PRTF response.
Since the silicone ear is smaller than the average ear, it would be logical to shift the target curve upwards so that the top of the curve is at 6 kHz.
Note: Don't use PRTF graphs for equalization. PRTF shows how the headphone can "excite" the pinna (mainly the concha). If PRTF matches the reference, no further equalization (or very minimal) is required after flat-plate equalization. However, if PRTF doesn't match the reference curve, only personal HRTF/PRTF measurement would be the solution.
Csaba Horváth
See also:
Headphone measurements: with or without ear?
Headphones & amplifiers - output impedance, load impedance and frequency response
High-resolution audio vs. 16 bit / 44.1kHz
Demonstration of sampling (interactive chart)
Noise perception, detection threshold & dynamic range
Audibility thresholds for SINAD / THD+N measurements
